The aluminum and aerospace industries have long sought a method to control recrystallization of aluminum alloys during deformation operations to permit the design of aluminum airframes with improved structural properties.
The metals industry today conventionally uses dispersoids, i.e., fine particles dispersed in the metal alloy, to control recrystallization and to increase dispersion strengthening at elevated temperatures. Such dispersoids of fine particles dispersed in the metal alloy usually are formed by solid state precipitation.
Recent developments in this area suggest that to improve formability and high temperature strength of aluminum alloys, it is necessary to increase the number densities and to reduce the size of the fine particle size dispersoids.
Certain emerging technologies are capable of producing fine particulates of different types with somewhat improved interfacial characteristics. Among the several ways of producing these materials, the technologies where the particles are introduced or formed in the molten aluminum prior to its solidification are attractive, primarily because of the potential for commercially economic processes on a large scale.
A variety of processing routes classified generally as in-situ ceramic phase formation processes in metal have been developed recently. According to the state of the reactants in the process, such a ceramic phase formation process in metal generally is classified into one of several categories:
(1) liquid metal-gas reaction, PA1 (2) liquid metal-liquid metal reaction, or PA1 (3) liquid-solid reaction.
In the case of carbon particles or carbon blocks in the context of liquid metal-liquid metal reactions or liquid-solid reactions, it is known that such carbon particles or carbon blocks are difficult to introduce directly into a melt in metal because of non-wetting of the carbon by the molten metal or alloy.